1. Field of the Invention
This invention concerns a shelf unit for joining to assemble a vertical member as a stud to a shelf or a chest.
2. Statement of the Related Art
A shelf unit can optionally select and change attaching positions of a shelf or a chest and includes those for assembling a book shelf or a display shelf by joining only the shelf with vertical members or those properly combining to assemble a shelf and a chest in accordance with the space of a room and application use.
The shelf comprises shelf plates for placing various articles which include an ordinary shelf plate, as well as a desk top plate for placing a display or a keyboard of a personal computer and a top plate for use in a table. Further, the chest has a box-like shape for accommodating various articles and includes cabinets of a hinged door type or a drawer type and magazine racks.
Most of existent shelf units have been assembled by joining two front and back vertical members to each of light and left ends of a shelf or a chest respectively. In a case where the joined portion has a structure, for example, as shown in FIG. 9, in which a vertical member 62 as a stud is clamped to an end face 61 of a shelf 60 by a single screw 63, when a heavy weight article is placed on the shelf 60, the vertical member 62 clamped to the end face 61 of the shelf 60 is caused to slid under the weight of the article in a direction rotating around the screw 63 as an axis as shown by the arrows in the drawing. Then, the shelf unit jolts in the forward-to-backward direction and the screw 60 for camping the vertical member 62 is slackened by the jolting to result in an extremely instable state of causing jolting not only in the forward-to-backward direction but also in the left to right direction in the shelf unit.
Therefore, when the vertical member 62 is clamped to the end face 61 of the shelf 60 by the single screw 63, an anti-jolting diagonal beam referred to as a cross bar or a cross brace is attached to the back of the shelf unit for stabilizing the shelf unit.
However, when the cross bar as the diagonal beam is attached to the back of the shelf unit, it entirely lacks in smart appearance which is not attractive. In addition, material cost is increased by so much as the attachment of the cross bar and it also results in a problem of increasing the number of assembling steps to bring bout a trouble in the assembly.
When the number of the screws for camping the vertical number to the end face of the shelf is increased, for example, by one and two screws are used, since the rotating torque around the screw as the axis does not exert, jolting of the shelf unit can be prevented without attaching the cross bar. However, since the number of the screws used is doubled, it results in a problem of taking more time for the assembly of the shelf unit then in a case of attaching the cross bar.
In view of the above, a technical subject of this invention is to prevent jolting of a shelf unit without attaching a cross bar even in a case where the joined portion between a shelf and a vertical member is clamped by a single screw.